At $STP$, 4 grams of $H_2$ will occupy how much volume in litres?

The correct option is D $44.8$
At $STP$, 4 $g$ of $H_2$ will occupy a volume of 44.8 $L$.
At $STP$, 1 mole of any gas occupies a volume of 22.4 $L$.
The atomic mass of $H_2$ is 2 $g/mol$.
The number of moles of $H_2$ in 4 $g$ is $\frac{4}{2}=2mol$.
Hence, 2 moles of $H_2$ at $STP$ will occupy a volume of $2\times 22.4=44.8L$